Plate lifting clamp



May 30, 1961 R. L. RENFROE PLATE LIFTING CLAMP 3 Sheets-Sheet 1 Filed Aug. 12, 1959 INVENTOR H07? 0 n c/ L. Renfroe.

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PLATE LIFTING CLAMP Filed Aug. 12, 1959 3 Sheets-Sheet 2 INVENTOR Raymond L Henfroe.

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PLATE LIFTING CLAMP Filed Aug. 12, 1959 5 Sheets-Sheet :5

INV E NTOR Raymond L. Renfl'Oe,

Unit

PLATE LIFTING CLAlVIl Raymond L. Renfroe, 1926 Spearing St., Jacksonville, Fla.

Filed Aug. 12, 1959, Ser. No. 833,163

14 Claims. (Cl. 294-101) This application relates to a plate lifting clamp, and is an improvement on the structure of the co-pending application of myself and Charles J. Renfroe, Serial No. 757,828, filed August 28, 1958, now Patent No. 2,916,- 321, granted December 8, 1959.

An object of the invention is to provide a clamp having the qualities of efficiency and ruggedness and capable of grasping and lifting plates of various sizes and weights, without marring the surfaces of the plates.

An additional object is to provide a clamp having a pivoted jaw, and a secondary jaw of special construction whereby the pivoted jaw has a minimum of movement, i.e. a short stroke.

A further object is to provide structure in a clamp which includes the pivoted jaw and a slidable jaw, the said jaws being retained within a unitary type of housing in their various positions of adjustment.

Another object is to provide in the penultimate construction a slidable wedge whereby to increase the grasping action of the clamp during the lifting operation, the clamp being so constructed that the heavier the weight, the tighter the grasp of the clamping jaws on the opposite sides of the plate or workpiece.

Yet another object is a clamp having a minimum number of parts for a clamp of this type which has both pivoted and slidable jaws for the purpose of grasping a plate on the opposite sides thereof.

Other objects will appear hereinafter throughout the specification.

In the drawings:

Figure 1 is a front elevational view of the clamp of this invention;

Figure 2 is a vertical section of the clamp, taken on the line 22 of Figure 4;

Figure 3 is a rear elevational view of the clamp of Figure 1;

Figure 4 is a side elevation showing one side of the clamp;

Figure 5 is a side elevation showing the opposite side of the clamp from that shown in Figure 4;

Figure 6 is a perspective view of the wedge jaw construction;

Figure 7 is a perspective view of the clamp casing with all parts removed;

Figure 8 is a perspective view of the connecting link with the lifting shackle attached thereto, the latter being partly broken away;

Figure 9 is a perspective view of the pivoted jaw; and

Figure 10 is a perspective view of the wedge adjusting guide nut.

The present invention is characterized by its ability to lift heavy loads without marring the surfaces of the plate or other workpiece during the lifting operation. The clamp is of the suspended type, i.e. it preferably is suspended from a traveling hook which is attached to a lifting crane.

Referring now to the drawings, 10 indicates the housing which, although preferably made from'a singlecast- 2,986,422 Patented May 30, 1961 ing, may be composed of a plurality of parts held together by threaded bolts. The housing 10 comprises a pair of platelike sides 12 and 14 which are held to each other by an integral connecting web 16. It will be noted that the side plates are provided on one side with lower curved ends 18 that extend below the lower curved ends 20, seen in Figures 3 and 4 for instance. The said ends 18 and 20 are spaced from each other for forming a slot 22, the latter being adapted to receive the plates or other workpiece designated by the letter A.

The hollow casing 10, as shown in Figure 2, is provided with pivoted jaw 24 having a plate-engaging surface 26. As shown in Figures 2 and 9, the pivoted jaw has an opening 28 which receives a pin 30 that may be a headed bolt having head 32 at one end and a cotter pin 34 at its opposite end.

The pivoted jaw has an upper portion provided with a slot 36 for the reception of a part, such as pin 38 of the connecting link 40. It will be understood, however, that instead of providing a slot on the pivoted jaw 24 and a pin on the connecting link 40, the connecting link 40 may be provided with the slot and the pivoted jaw 24 provided with a pin, without affecting the operation of the pivoted jaw 24.

Connecting link 41) is pivotally held in position by a pin 42 which connects the plates 12 and 14 and extends through sleeve 42a, see Figure 2. The opposite endof the link 40 is connected by a pivot 44 to the lifting shackle 46. The upper end of the lifting shackle may be provided with an opening 48, or the shape of the upper end of the shackle may be that of a hook, not shown. However, I prefer to provide the opening 48, which may be engaged by the hook end of a hoist.

Stop pins 50 limit the upward swinging movementof the connecting link 48 and thereby restrict the movement of the pivoted jaw into and out of the slot or opening 22. The stop pins 50 also restrict the upward movement of the shackle 46.

In order to compensate for the small amount of movement of the jaw 24, there is provided a sliding wedge 52 having an extended gripping surface 54 which faces the surface 26 of pivoted jaw 24 at the opposite end of the slot. The gripping surface normally extends into the slot as seen in Figures 1 and 2.

The wedge 52 is guided in its upward and downward movement of adjustment in the casing 10 by means of a nut 56, as seen in Figures 2, 6 and 10. The sides of the nut 56 are provided with stepped portions 58 that slide on facing grooves 68 of the wedge 52. Nut 56 is further anchored in position by means of a bolt 62 having threads 64 that engage threads 66 of nut 56. Bolt 62 is provided with a knurled head 68 and a hexagonal socket 70 whereby this bolt may be adjusted either by hand or by a socket wrench when using the socket 70.

As will be seen by referring to Figures 2 and'7, the bolt 62 extends loosely and non-threadedly through the opening 72 of the web 16 that connects side plates IZ-and 14. Wedge 52 is adjustable vertically in the casing 10, as seen in Figure 2, by means of the bolt 74. This bolt is provided with an octagonal head '76 and a screw-threaded shank portion 78 which threadedly engages the nut 80. The sliding wedge 52 has flat sides 82 that clear the flat sides of the side plates 12 and 14 of the housing. The nut 88 is connected to the wedge sides by means of a pin and hole connection shown at 84 in Figures 4 and 6.

As shown in Figure 6, the bolt 74 is guided by a sleeve 86. This sleeve, as shown in Figure 4, extends between the upper portions of the plates 12 and 14 and'is held between the side plates 12 and 14 by means of knurled stud members 88 and $8, each one of which threadedly engages the side plates and is provided with a stud member 92, only one of which is shown in Figure 4, that engages a central aperture 94 in the sleeve 86. This sleeve, therefore, is rotatable on the stud members 92. Extending transversely through this sleeve, with reference to opening 94 of sleeve 86, is an opening 96 that freely supports and. guides the bolt 74. The bolt is held in position on the sleeve 86 by the head 76, and a locking nut 98, which is held in locking position on the bolt 74 by means of a threaded pin 100. 7

It will be noted from the foregoing, therefore, that the workpiece A may be inserted in the slot 22. The head 76 of bolt 74 is then engaged by a suitable tool and the bolt is rotated to cause the wedge 52 to move downwardly and inwardly of the slot 22 from the full line position to the dotted line position of Figure 2, for example. In this position the work is firmly engaged between the surface 26 of the pivoted jaw 24 and surface 54 of the wedge 52. The opening 48 of the lifting shackle 46 is now engaged by a hook of the hoist, not shown. When an upwardly moving force is applied to the lifting shackle, the pivoted jaw 24 tends to move from the dotted line position to the full line position, both shown in Figure 2. When the load is lifted by means of the shackle bolt and the hoisting mechanism, any tendency of the workpiece to shift or move downwardly would be opposed by the action of the wedge 52 on one side and the pivoted jaw 24 on the opposite side, the result being a positive clamping engagement along an extended surface of the workpiece by the wedge 52 and a positive grasp on the opposite side by the surface 26 of the pivoted jaw 24. An additional locking effect may be had by inserting a socket wrench in the socket 70 and operating the bolt 62 to positively lock the wedge 52 in engagement with the workpiece. By means of the primary adjustment of the wedge 52, the movement of the pivoted jaw 24 may be reduced to a minimum about the pin or pivot 30, in order to positively and graspingly engage the work by the pivoted jaw 24.

It will be noted that wedge 52 is both slidingly and pivotally supported in casing 10 by bolt 74 through the threaded engagement of bolt 74 with nut 80, and sleeve 86 with its pivoted supporting stud members 92. The wedge may be caused to pivot and lockingly engage the work in its pivoted movement by means of the engagement of nut 56 by bolt 62.

The above description and drawings disclose a single embodiment of the invention, and specific language has been employed in describing the several figures. It will, nevertheless, be understood that no limitations of the scope of the invention are thereby contemplated, and that various alterations and modifications may be made such as would occur to one skilled in the art to which the invention relates.

I claim:

1. A clamp comprising a housing having sides, said sides having aligned substantially transverse openings forming an upwardly extending slot when the longitudinal axis of said casing is in a vertical plane, a first jaw, means pivoting said jaw in said casing adjacent one side of said slot for movement in said slot whereby to engage the work, means for moving said first jaw into and out of work-engaging position including lever means, one end of said lever means and said first jaw comprising members, one of said members having a slot engaging part and the other of said members having a slot into which said slot engaging part extends, actuating link means adapted to support said casing with its longitudinal axis in a vertical plane, means pivotally connecting the lower end of said actuating link means to the opposite end of said first named lever means from said end connected to said pivoted first jaw, and a second jaw located on the opposite side of said slot from said first jaw and adapted to extend into said first named slot when actuated to thereby engage the work, and means for slidably supporting and adjustably moving said second jaw in said casing including a threaded member and a pivotally connecting member for connecting said threaded member to said second jaw, whereby when said last named means is actuated said slidable jaw may be moved toward and away from said first jaw, said first jaw and said first named lever means, and said second jaw and said means for supporting and moving the same being substantially confined within said casing.

2. The structure of claim 1 wherein said second jaw is provided with wedge means whereby said second named jaw is supported for movement into and out of said slot, and means for locking said second jaw in said slot.

3 The structure of claim 2 wherein said locking means comprises a bolt mounted in said casing, said bolt having a screw-threaded connection with said second jaw.

4. The structure of claim 1 wherein said means for slidably supporting and adjustably moving said second jaw additionally includes cooperating engaging wedge surfaces on said casing and second jaw.

5. The structure of claim 4 wherein said means for slidably supporting and adjustably moving said second jaw further includes juxtaposed grooves on said second jaw, a nut having means engaging said grooves, and a bolt supported on said casing threadedly engaging said nut.

6. The structure of claim 1 wherein said means for slidably supporting and adjustably moving said second jaw additionally includes a nut on said wedge, said nut having threads, a bolt having threads adjacent its end engaging said nut, and means for supporting said bolt in said casing comprising a sleeve having an aperture through which said bolt freely extends, said sleeve having a transverse passageway, and stud means engaging said passageway for pivotally supporting said sleeve in said casing.

7. A clamp comprising a housing having sides, said sides having aligned substantially transverse openings forming an upwardly extending slot when the longitudinal axis of said casing is in a vertical plane, a first jaw, means pivoting said jaw in said casing adjacent one side of said slot for movement in said slot whereby to engage the work, means for moving said first jaw into and out oi work-engaging position including lever means, one end of said lever means having a slot engaging part, and said first jaw having a slot into which said slot engaging part extends, actuating link means adapted to support said casing with its longitudinal axis in a vertical plane, means pivotally connecting the lower end of said actuating link means to the opposite end of said first named lever means from said end connected to said pivoted first jaw, and a second jaw located on the opposite side of said slot from said first jaw and adapted to extend into said first named slot when actuated to thereby engage the work, and means for slidably supporting and adjustably moving said second jaw in said casing including a threaded member and a pivotally connecting member for connecting said threaded member to said second jaw whereby when said last named means is actuated said slidable jaw may be moved toward and away from said first jaw, said first jaw and said first named lever means, and said second jaw and said means for supporting and moving the same being substantially confined within said casing.

8. The structure of claim 7 wherein said second jaw is provided with wedge means whereby said second named jaw is supported for movement into and out of said slot, and means for locking said second jaw in said slot.

9. The structure of claim 8 wherein said locking means comprises a bolt mounted in said casing, said bolt having a screw-threaded connection with said second jaw.

10. The structure of claim 7 wherein said means for slidably supporting and adjustably moving said second jaw additionally includes cooperating engaging wedge surfaces on said casing and second jaw.

11. The structure of claim 10 wherein said means for slidably supporting and adjustably moving said second jaw further includes juxtaposed grooves on said second jaw, a not having means engaging said grooves, and a bolt supported on said casing threadedly engaging said nut.

12. The structure of claim 7 wherein said means for slidably supporting and adjustably moving said second jaw additionally includes a nut on said wedge, said nut having threads, a bolt having threads adjacent its end engaging said nut, and means for supporting said bolt in said casing comprising a sleeve having an aperture through which said bolt freely extends, said sleeve having a transverse passageway, and stud means engaging said passageway for pivotally supporting said sleeve in said casing.

13. A clamp comprising a housing having sides, said sides having aligned substantially transverse openings forming an upwardly extending slot when the longitudinal axis of said casing is in a vertical plane, a first jaw, means pivoting said jaw in said casing adjacent one side of said slot for movement in said slot whereby to engage the work, means for moving said first jaw into and out of work-engaging position including lever means, one end of said lever means and said first jaw comprising members, one of said members having a slot engaging part and the other of said members having a slot into which said slot engaging part extends, actuating link means adapted to support said casing with its longitudinal axis in a vertical plane, means pivotally connecting the lower end of said actuating link means to the opposite end of said first named lever means from said end connected to said pivoted first jaw, and a second jaw located on the opposite side of said slot from said first jaw and adapted to extend into said first named slot when actuated to thereby engage the work, and means for slidably and pivotally supporting and adjustably moving said second jaw in said casing including a threaded member and a pivotally connecting member for connecting said threaded member to said second jaw, whereby when said last named means is actuated said slidable jaw may be moved toward and away from said first jaw; said first jaw and said first named lever means, and said second jaw and said means for supporting and moving the same being substantially confined Within said casing.

14. A clamp comprising a housing having sides, said sides having aligned substantially transverse openings forming an upwardly extending slot when the longitudinal axis of said casing is in a vertical plane, a first jaw, means pivoting said jaw in said casing adjacent one side of said slot for movement in said slot whereby to engage the work, means for moving said first jaw into and out of work-engaging position including lever means, one end of said lever means having a stud, and said first jaw having a slot into which said stud extends, actuating link means adapted to support said casing with its longitudinal axis in a vertical plane, means pivotally connecting the lower end of said actuating link means to the opposite end of said first named lever means from said end connected to said pivoted first jaw, and a second jaw located on the opposite side of said slot from said first jaw and adapted to extend into said first named slot when actuated to thereby engage the work, and means for slidably and pivotally supporting and adjustably moving said second jaw in said casing including a threaded member and a pivotally connecting member for connecting said threaded member to said second jaw, whereby when said last named means is actuated said slidable jaw may be moved toward and away from said first jaw; said first jaw and said first named lever means, and said second jaw and said means for supporting and moving the same being substantially confined within said casing.

References Cited in the file of this patent UNITED STATES PATENTS 1,221,400 Wilhelm et a1. Apr. 3, 1917 2,284,006 McLellan May 26, 1942 2,347,361 Nelson Apr. 25, 1944 2,347,922 Nelson May 2, 1944 2,360,602 Waldrup Oct. 17, 1944 2,387,408 Pertuit Oct. 23, 1945 2,446,610 Renfroe Aug. 10, 1948 2,461,394 Plante Feb. 8, 1949 FOREIGN PATENTS 42,45 0 Norway Feb. 8, 1926 

